1. Field of the Invention
The present invention relates to an information storage element and a method of writing information into and reading information from the information storage element.
2. Description of the Related Art
In information devices such as computers, currently, a hard disk drive is widely used as an external storage unit. However, since a hard disk drive includes a rotation mechanism, it is difficult to reduce the size thereof and to save electric power. Consequently, a silicon disk drive (solid-state drive (SSD)) including a flash memory has started to be used as an external storage unit for a small device. However, such a silicon disk drive is expensive and the storage capacity thereof is not sufficient. Therefore, a storage unit which has a large storage capacity, which is non-volatile, and into and from which information can be written and read at a high speed has been strongly desired.
As one of such storage units, a current-induced domain wall motion magnetic memory, which is a memory developed from a magnetic memory configured to store information as a magnetization state of a magnetic material, has been devised (refer to, for example, Japanese Unexamined Patent Application Publication Nos. 2005-123617 and 2006-237183). In such a current-induced domain wall motion magnetic memory, a strip-shaped ferromagnetic material layer is divided into a plurality of magnetization regions (magnetic domains), and a current is applied to the ferromagnetic material layer, whereby information is written into or read from the magnetization regions of the ferromagnetic material layer while moving a domain wall, which is a boundary of the magnetization regions.